Performing a two-step random access channel procedure

ABSTRACT

Apparatuses, methods, and systems are disclosed for performing a two-step random access channel procedure. One method includes determining whether to perform a two-step random access channel procedure or a four-step random access channel procedure. The method includes, in response to determining to perform the two-step random access channel procedure: in a first step: transmitting a preamble in a first time slot; and transmitting an uplink data transmission via a physical uplink shared channel in a second time slot different from the first time slot; and, in a second step, receiving a response message corresponding to the first step, wherein the response message comprises a radio network temporary identifier.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. patent application Ser. No.16/584,249 filed on Sep. 26, 2019, which is a continuation of U.S.Patent Application Ser. No. 62/736,928 entitled “A RANDOM ACCESSPROCEDURE WITH A REDUCED NUMBER OF SIGNALING MESSAGES” and filed on Sep.26, 2018 for Joachim Loehr, all of which are incorporated herein byreference in their entirety.

FIELD

The subject matter disclosed herein relates generally to wirelesscommunications and more particularly relates to performing a two-steprandom access channel procedure.

BACKGROUND

The following abbreviations are herewith defined, at least some of whichare referred to within the following description: Third GenerationPartnership Project (“3GPP”), 5^(th) Generation (“5G”),Positive-Acknowledgment (“ACK”), Aggregation Level (“AL”), Access andMobility Management Function (“AMF”), Access Point (“AP”), Beam FailureDetection (“BFD”), Binary Phase Shift Keying (“BPSK”), Base Station(“BS”), Buffer Status Report (“BSR”), Bandwidth (“BW”), Bandwidth Part(“BWP”), Cell RNTI (“C-RNTI”), Carrier Aggregation (“CA”),Contention-Based Random Access (“CBRA”), Clear Channel Assessment(“CCA”), Common Control Channel (“CCCH”), Control Channel Element(“CCE”), Cyclic Delay Diversity (“CDD”), Code Division Multiple Access(“CDMA”), Control Element (“CE”), Contention-Free Random Access(“CFRA”), Closed-Loop (“CL”), Coordinated Multipoint (“CoMP”), ChannelOccupancy Time (“COT”), Cyclic Prefix (“CP”), Cyclical Redundancy Check(“CRC”), Channel State Information (“CSI”), Channel StateInformation-Reference Signal (“CSI-RS”), Common Search Space (“CSS”),Control Resource Set (“CORESET”), Discrete Fourier Transform Spread(“DFTS”), Downlink Control Information (“DCI”), Downlink (“DL”),Demodulation Reference Signal (“DMRS”), Data Radio Bearer (“DRB”),Discontinuous Reception (“DRX”), Downlink Pilot Time Slot (“DwPTS”),Enhanced Clear Channel Assessment (“eCCA”), Enhanced Mobile Broadband(“eMBB”), Evolved Node B (“eNB”), Effective Isotropic Radiated Power(“EIRP”), European Telecommunications Standards Institute (“ETSI”),Frame Based Equipment (“FBE”), Frequency Division Duplex (“FDD”),Frequency Division Multiplexing (“FDM”), Frequency Division MultipleAccess (“FDMA”), Frequency Division Orthogonal Cover Code (“FD-OCC”), 5GNode B or Next Generation Node B (“gNB”), General Packet Radio Services(“GPRS”), Guard Period (“GP”), Global System for Mobile Communications(“GSM”), Globally Unique Temporary UE Identifier (“GUTI”), Home AMF(“hAMF”), Hybrid Automatic Repeat Request (“HARQ”), Home LocationRegister (“HLR”), Handover (“HO”), Home PLMN (“HPLMN”), Home SubscriberServer (“HSS”), Identity or Identifier (“ID”), Information Element(“IE”), International Mobile Equipment Identity (“IMEI”), InternationalMobile Subscriber Identity (“IMSI”), International MobileTelecommunications (“IMT”), Internet-of-Things (“IoT”), Layer 2 (“L2”),Licensed Assisted Access (“LAA”), Load Based Equipment (“LBE”),Listen-Before-Talk (“LBT”), Logical Channel (“LCH”), Logical ChannelPrioritization (“LCP”), Log-Likelihood Ratio (“LLR”), Long TermEvolution (“LTE”), Multiple Access (“MA”), Medium Access Control(“MAC”), Multimedia Broadcast Multicast Services (“MBMS”), ModulationCoding Scheme (“MCS”), Master Information Block (“MIB”), Multiple InputMultiple Output (“MIMO”), Mobility Management (“MM”), MobilityManagement Entity (“MIME”), Mobile Network Operator (“MNO”), massive MTC(“mMTC”), Maximum Power Reduction (“MPR”), Machine Type Communication(“MTC”), Multi User Shared Access (“MUSA”), Non Access Stratum (“NAS”),Narrowband (“NB”), Negative-Acknowledgment (“NACK”) or (“NAK”), NetworkEntity (“NE”), Network Function (“NF”), Non-Orthogonal Multiple Access(“NOMA”), New Radio (“NR”), NR Unlicensed (“NR-U”), Network RepositoryFunction (“NRF”), Network Slice Instance (“NSI”), Network SliceSelection Assistance Information (“NSSAI”), Network Slice SelectionFunction (“NS SF”), Network Slice Selection Policy (“NSSP”), Operationand Maintenance System (“OAM”), Orthogonal Frequency DivisionMultiplexing (“OFDM”), Open-Loop (“OL”), Other System Information(“OSI”), Power Angular Spectrum (“PAS”), Physical Broadcast Channel(“PBCH”), Power Control (“PC”), Primary Cell (“PCell”), Policy ControlFunction (“PCF”), Physical Cell ID (“PCID”), Physical Downlink ControlChannel (“PDCCH”), Packet Data Convergence Protocol (“PDCP”), PhysicalDownlink Shared Channel (“PDSCH”), Pattern Division Multiple Access(“PDMA”), Packet Data Unit (“PDU”), Physical Hybrid ARQ IndicatorChannel (“PHICH”), Power Headroom (“PH”), Power Headroom Report (“PHR”),Physical Layer (“PHY”), Public Land Mobile Network (“PLMN”), PhysicalRandom Access Channel (“PRACH”), Physical Resource Block (“PRB”),Primary Secondary Cell (“PSCell”), Physical Uplink Control Channel(“PUCCH”), Physical Uplink Shared Channel (“PUSCH”), Quasi Co-Located(“QCL”), Quality of Service (“QoS”), Quadrature Phase Shift Keying(“QPSK”), Registration Area (“RA”), RA RNTI (“RA-RNTI”), Radio AccessNetwork (“RAN”), Radio Access Technology (“RAT”), Random AccessProcedure (“RACH”), Random Access Preamble Identifier (“RAPID”), RandomAccess Response (“RAR”), Resource Element Group (“REG”), Radio LinkControl (“RLC”), RLC Acknowledged Mode (“RLC-AM”), RLC UnacknowledgedMode/Transparent Mode (“RLC-UM/TM”), Radio Link Monitoring (“RLM”),Radio Network Temporary Identifier (“RNTI”), Reference Signal (“RS”),Remaining Minimum System Information (“RMSI”), Radio Resource Control(“RRC”), Radio Resource Management (“RRM”), Resource Spread MultipleAccess (“RSMA”), Reference Signal Received Power (“RSRP”), Round TripTime (“RTT”), Receive (“RX”), Sparse Code Multiple Access (“SCMA”),Scheduling Request (“SR”), Sounding Reference Signal (“SRS”), SingleCarrier Frequency Division Multiple Access (“SC-FDMA”), Secondary Cell(“SCell”), Shared Channel (“SCH”), Sub-carrier Spacing (“SCS”), ServiceData Unit (“SDU”), System Information Block (“SIB”),SystemInformationBlockType1 (“SIB1”), SystemInformationBlockType2(“SIB2”), Sub scriber Identity/Identification Module (“SIM”),Signal-to-Interference-Plus-Noise Ratio (“SINR”), Service LevelAgreement (“SLA”), Session Management Function (“SMF”), Special Cell(“SpCell”), Single Network Slice Selection Assistance Information(“S-NSSAI”), Signaling Radio Bearer (“SRB”), Shortened TTI (“sTTI”),Synchronization Signal (“SS”), Synchronization Signal Block (“SSB”),Supplementary Uplink (“SUL”), Subscriber Permanent Identifier (“SUPI”),Timing Advance (“TA”), Timing Alignment Timer (“TAT”), Transport Block(“TB”), Transport Block Size (“TBS”), Time-Division Duplex (“TDD”), TimeDivision Multiplex (“TDM”), Time Division Orthogonal Cover Code(“TD-OCC”), Transmission Power Control (“TPC”), Transmission ReceptionPoint (“TRP”), Transmission Time Interval (“TTI”), Transmit (“TX”),Uplink Control Information (“UCI”), Unified Data Management Function(“UDM”), Unified Data Repository (“UDR”), User Entity/Equipment (MobileTerminal) (“UE”), Uplink (“UL”), UL SCH (“UL-SCH”), Universal MobileTelecommunications System (“UMTS”), User Plane (“UP”), Uplink Pilot TimeSlot (“UpPTS”), Ultra-reliability and Low-latency Communications(“URLLC”), UE Route Selection Policy (“URSP”), Visiting AMF (“vAMF”),Visiting NSSF (“vNSSF”), Visiting PLMN (“VPLMN”), and WorldwideInteroperability for Microwave Access (“WiMAX”).

In certain wireless communications networks, a RACH procedure may beused. In such networks, the RACH procedure may take longer than desired.

BRIEF SUMMARY

Methods for performing a two-step random access channel procedure aredisclosed. Apparatuses and systems also perform the functions of themethods. One embodiment of a method includes determining whether toperform a two-step random access channel procedure or a four-step randomaccess channel procedure. In some embodiments, the method includes, inresponse to determining to perform the two-step random access channelprocedure: in a first step: transmitting a preamble in a first timeslot; and transmitting an uplink data transmission via a physical uplinkshared channel in a second time slot different from the first time slot;and, in a second step, receiving a response message corresponding to thefirst step, wherein the response message comprises a radio networktemporary identifier.

One apparatus for performing a two-step random access channel procedureincludes a processor that determines whether to perform a two-steprandom access channel procedure or a four-step random access channelprocedure. In various embodiment, the apparatus includes a transmitter.In certain embodiments, the apparatus includes a receiver. In someembodiments, in response to determining to perform the two-step randomaccess channel procedure: in a first step, the transmitter: transmits apreamble in a first time slot; and transmits an uplink data transmissionvia a physical uplink shared channel in a second time slot differentfrom the first time slot; and in a second step, the receiver receives aresponse message corresponding to the first step, wherein the responsemessage comprises a radio network temporary identifier.

Another embodiment of a method for performing a two-step random accesschannel procedure includes receiving a preamble in a first time slot andreceiving an uplink data transmission via a physical uplink sharedchannel in a second time slot different from the first time slot inresponse to a determination by a remote unit to perform a two-steprandom access channel procedure. In some embodiments, the methodincludes transmitting a response message corresponding to the preambleand the uplink data transmission, wherein the response message comprisesa radio network temporary identifier.

One apparatus for performing a two-step random access channel procedureincludes a receiver that receives a preamble in a first time slot andreceiving an uplink data transmission via a physical uplink sharedchannel in a second time slot different from the first time slot inresponse to a determination by a remote unit to perform a two-steprandom access channel procedure. In certain embodiments, the apparatusincludes a transmitter that transmits a response message correspondingto the preamble and the uplink data transmission, wherein the responsemessage comprises a radio network temporary identifier.

BRIEF DESCRIPTION OF THE DRAWINGS

A more particular description of the embodiments briefly described abovewill be rendered by reference to specific embodiments that areillustrated in the appended drawings. Understanding that these drawingsdepict only some embodiments and are not therefore to be considered tobe limiting of scope, the embodiments will be described and explainedwith additional specificity and detail through the use of theaccompanying drawings, in which:

FIG. 1 is a schematic block diagram illustrating one embodiment of awireless communication system for performing a two-step random accesschannel procedure;

FIG. 2 is a schematic block diagram illustrating one embodiment of anapparatus that may be used for performing a two-step random accesschannel procedure;

FIG. 3 is a schematic block diagram illustrating one embodiment of anapparatus that may be used for performing a two-step random accesschannel procedure;

FIG. 4 is a communication diagram illustrating one embodiment ofcommunications as part of a RACH procedure;

FIG. 5 is a communication diagram illustrating another embodiment ofcommunications as part of a RACH procedure;

FIG. 6 is a resource diagram illustrating a time offset and a frequencyoffset;

FIG. 7 is a flow chart diagram illustrating one embodiment of a methodfor performing a two-step random access channel procedure; and

FIG. 8 is a flow chart diagram illustrating another embodiment of amethod for performing a two-step random access channel procedure.

DETAILED DESCRIPTION

As will be appreciated by one skilled in the art, aspects of theembodiments may be embodied as a system, apparatus, method, or programproduct. Accordingly, embodiments may take the form of an entirelyhardware embodiment, an entirely software embodiment (includingfirmware, resident software, micro-code, etc.) or an embodimentcombining software and hardware aspects that may all generally bereferred to herein as a “circuit,” “module” or “system.” Furthermore,embodiments may take the form of a program product embodied in one ormore computer readable storage devices storing machine readable code,computer readable code, and/or program code, referred hereafter as code.The storage devices may be tangible, non-transitory, and/ornon-transmission. The storage devices may not embody signals. In acertain embodiment, the storage devices only employ signals foraccessing code.

Certain of the functional units described in this specification may belabeled as modules, in order to more particularly emphasize theirimplementation independence. For example, a module may be implemented asa hardware circuit comprising custom very-large-scale integration(“VLSI”) circuits or gate arrays, off-the-shelf semiconductors such aslogic chips, transistors, or other discrete components. A module mayalso be implemented in programmable hardware devices such as fieldprogrammable gate arrays, programmable array logic, programmable logicdevices or the like.

Modules may also be implemented in code and/or software for execution byvarious types of processors. An identified module of code may, forinstance, include one or more physical or logical blocks of executablecode which may, for instance, be organized as an object, procedure, orfunction. Nevertheless, the executables of an identified module need notbe physically located together, but may include disparate instructionsstored in different locations which, when joined logically together,include the module and achieve the stated purpose for the module.

Indeed, a module of code may be a single instruction, or manyinstructions, and may even be distributed over several different codesegments, among different programs, and across several memory devices.Similarly, operational data may be identified and illustrated hereinwithin modules, and may be embodied in any suitable form and organizedwithin any suitable type of data structure. The operational data may becollected as a single data set, or may be distributed over differentlocations including over different computer readable storage devices.Where a module or portions of a module are implemented in software, thesoftware portions are stored on one or more computer readable storagedevices.

Any combination of one or more computer readable medium may be utilized.The computer readable medium may be a computer readable storage medium.The computer readable storage medium may be a storage device storing thecode. The storage device may be, for example, but not limited to, anelectronic, magnetic, optical, electromagnetic, infrared, holographic,micromechanical, or semiconductor system, apparatus, or device, or anysuitable combination of the foregoing.

More specific examples (a non-exhaustive list) of the storage devicewould include the following: an electrical connection having one or morewires, a portable computer diskette, a hard disk, a random access memory(“RAM”), a read-only memory (“ROM”), an erasable programmable read-onlymemory (“EPROM” or Flash memory), a portable compact disc read-onlymemory (“CD-ROM”), an optical storage device, a magnetic storage device,or any suitable combination of the foregoing. In the context of thisdocument, a computer readable storage medium may be any tangible mediumthat can contain, or store a program for use by or in connection with aninstruction execution system, apparatus, or device.

Code for carrying out operations for embodiments may be any number oflines and may be written in any combination of one or more programminglanguages including an object oriented programming language such asPython, Ruby, Java, Smalltalk, C++, or the like, and conventionalprocedural programming languages, such as the “C” programming language,or the like, and/or machine languages such as assembly languages. Thecode may execute entirely on the user's computer, partly on the user'scomputer, as a stand-alone software package, partly on the user'scomputer and partly on a remote computer or entirely on the remotecomputer or server. In the latter scenario, the remote computer may beconnected to the user's computer through any type of network, includinga local area network (“LAN”) or a wide area network (“WAN”), or theconnection may be made to an external computer (for example, through theInternet using an Internet Service Provider).

Reference throughout this specification to “one embodiment,” “anembodiment,” or similar language means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment. Thus, appearances of the phrases“in one embodiment,” “in an embodiment,” and similar language throughoutthis specification may, but do not necessarily, all refer to the sameembodiment, but mean “one or more but not all embodiments” unlessexpressly specified otherwise. The terms “including,” “comprising,”“having,” and variations thereof mean “including but not limited to,”unless expressly specified otherwise. An enumerated listing of itemsdoes not imply that any or all of the items are mutually exclusive,unless expressly specified otherwise. The terms “a,” “an,” and “the”also refer to “one or more” unless expressly specified otherwise.

Furthermore, the described features, structures, or characteristics ofthe embodiments may be combined in any suitable manner. In the followingdescription, numerous specific details are provided, such as examples ofprogramming, software modules, user selections, network transactions,database queries, database structures, hardware modules, hardwarecircuits, hardware chips, etc., to provide a thorough understanding ofembodiments. One skilled in the relevant art will recognize, however,that embodiments may be practiced without one or more of the specificdetails, or with other methods, components, materials, and so forth. Inother instances, well-known structures, materials, or operations are notshown or described in detail to avoid obscuring aspects of anembodiment.

Aspects of the embodiments are described below with reference toschematic flowchart diagrams and/or schematic block diagrams of methods,apparatuses, systems, and program products according to embodiments. Itwill be understood that each block of the schematic flowchart diagramsand/or schematic block diagrams, and combinations of blocks in theschematic flowchart diagrams and/or schematic block diagrams, can beimplemented by code. The code may be provided to a processor of ageneral purpose computer, special purpose computer, or otherprogrammable data processing apparatus to produce a machine, such thatthe instructions, which execute via the processor of the computer orother programmable data processing apparatus, create means forimplementing the functions/acts specified in the schematic flowchartdiagrams and/or schematic block diagrams block or blocks.

The code may also be stored in a storage device that can direct acomputer, other programmable data processing apparatus, or other devicesto function in a particular manner, such that the instructions stored inthe storage device produce an article of manufacture includinginstructions which implement the function/act specified in the schematicflowchart diagrams and/or schematic block diagrams block or blocks.

The code may also be loaded onto a computer, other programmable dataprocessing apparatus, or other devices to cause a series of operationalsteps to be performed on the computer, other programmable apparatus orother devices to produce a computer implemented process such that thecode which execute on the computer or other programmable apparatusprovide processes for implementing the functions/acts specified in theflowchart and/or block diagram block or blocks.

The schematic flowchart diagrams and/or schematic block diagrams in theFigures illustrate the architecture, functionality, and operation ofpossible implementations of apparatuses, systems, methods and programproducts according to various embodiments. In this regard, each block inthe schematic flowchart diagrams and/or schematic block diagrams mayrepresent a module, segment, or portion of code, which includes one ormore executable instructions of the code for implementing the specifiedlogical function(s).

It should also be noted that, in some alternative implementations, thefunctions noted in the block may occur out of the order noted in theFigures. For example, two blocks shown in succession may, in fact, beexecuted substantially concurrently, or the blocks may sometimes beexecuted in the reverse order, depending upon the functionalityinvolved. Other steps and methods may be conceived that are equivalentin function, logic, or effect to one or more blocks, or portionsthereof, of the illustrated Figures.

Although various arrow types and line types may be employed in theflowchart and/or block diagrams, they are understood not to limit thescope of the corresponding embodiments. Indeed, some arrows or otherconnectors may be used to indicate only the logical flow of the depictedembodiment. For instance, an arrow may indicate a waiting or monitoringperiod of unspecified duration between enumerated steps of the depictedembodiment. It will also be noted that each block of the block diagramsand/or flowchart diagrams, and combinations of blocks in the blockdiagrams and/or flowchart diagrams, can be implemented by specialpurpose hardware-based systems that perform the specified functions oracts, or combinations of special purpose hardware and code.

The description of elements in each figure may refer to elements ofproceeding figures. Like numbers refer to like elements in all figures,including alternate embodiments of like elements.

FIG. 1 depicts an embodiment of a wireless communication system 100 forperforming a two-step random access channel procedure. In oneembodiment, the wireless communication system 100 includes remote units102 and network units 104. Even though a specific number of remote units102 and network units 104 are depicted in FIG. 1 , one of skill in theart will recognize that any number of remote units 102 and network units104 may be included in the wireless communication system 100.

In one embodiment, the remote units 102 may include computing devices,such as desktop computers, laptop computers, personal digital assistants(“PDAs”), tablet computers, smart phones, smart televisions (e.g.,televisions connected to the Internet), set-top boxes, game consoles,security systems (including security cameras), vehicle on-boardcomputers, network devices (e.g., routers, switches, modems), aerialvehicles, drones, or the like. In some embodiments, the remote units 102include wearable devices, such as smart watches, fitness bands, opticalhead-mounted displays, or the like. Moreover, the remote units 102 maybe referred to as subscriber units, mobiles, mobile stations, users,terminals, mobile terminals, fixed terminals, subscriber stations, UE,user terminals, a device, or by other terminology used in the art. Theremote units 102 may communicate directly with one or more of thenetwork units 104 via UL communication signals.

The network units 104 may be distributed over a geographic region. Incertain embodiments, a network unit 104 may also be referred to as anaccess point, an access terminal, a base, a base station, a Node-B, aneNB, a gNB, a Home Node-B, a relay node, a device, a core network, anaerial server, a radio access node, an AP, NR, a network entity, an AMF,a UDM, a UDR, a UDM/UDR, a PCF, a RAN, an NSSF, or by any otherterminology used in the art. The network units 104 are generally part ofa radio access network that includes one or more controllerscommunicably coupled to one or more corresponding network units 104. Theradio access network is generally communicably coupled to one or morecore networks, which may be coupled to other networks, like the Internetand public switched telephone networks, among other networks. These andother elements of radio access and core networks are not illustrated butare well known generally by those having ordinary skill in the art.

In one implementation, the wireless communication system 100 iscompliant with NR protocols standardized in 3GPP, wherein the networkunit 104 transmits using an OFDM modulation scheme on the DL and theremote units 102 transmit on the UL using a SC-FDMA scheme or an OFDMscheme. More generally, however, the wireless communication system 100may implement some other open or proprietary communication protocol, forexample, WiMAX, IEEE 802.11 variants, GSM, GPRS, UMTS, LTE variants,CDMA2000, Bluetooth®, ZigBee, Sigfoxx, among other protocols. Thepresent disclosure is not intended to be limited to the implementationof any particular wireless communication system architecture orprotocol.

The network units 104 may serve a number of remote units 102 within aserving area, for example, a cell or a cell sector via a wirelesscommunication link. The network units 104 transmit DL communicationsignals to serve the remote units 102 in the time, frequency, and/orspatial domain.

In one embodiment, a remote unit 102 may determine whether to perform atwo-step random access channel procedure or a four-step random accesschannel procedure. In some embodiments, the remote unit 102 may, inresponse to determining to perform the two-step random access channelprocedure: in a first step: transmit a preamble in a first time slot;and transmit an uplink data transmission via a physical uplink sharedchannel in a second time slot different from the first time slot; and,in a second step, receive a response message corresponding to the firststep, wherein the response message comprises a radio network temporaryidentifier. Accordingly, the remote unit 102 may be used for performinga two-step random access channel procedure.

In certain embodiments, a network unit 104 may receive a preamble in afirst time slot and receiving an uplink data transmission via a physicaluplink shared channel in a second time slot different from the firsttime slot in response to a determination by a remote unit to perform atwo-step random access channel procedure. In some embodiments, thenetwork unit 104 may transmit a response message corresponding to thepreamble and the uplink data transmission, wherein the response messagecomprises a radio network temporary identifier. Accordingly, the networkunit 104 may be used for performing a two-step random access channelprocedure.

FIG. 2 depicts one embodiment of an apparatus 200 that may be used forperforming a two-step random access channel procedure. The apparatus 200includes one embodiment of the remote unit 102. Furthermore, the remoteunit 102 may include a processor 202, a memory 204, an input device 206,a display 208, a transmitter 210, and a receiver 212. In someembodiments, the input device 206 and the display 208 are combined intoa single device, such as a touchscreen. In certain embodiments, theremote unit 102 may not include any input device 206 and/or display 208.In various embodiments, the remote unit 102 may include one or more ofthe processor 202, the memory 204, the transmitter 210, and the receiver212, and may not include the input device 206 and/or the display 208.

The processor 202, in one embodiment, may include any known controllercapable of executing computer-readable instructions and/or capable ofperforming logical operations. For example, the processor 202 may be amicrocontroller, a microprocessor, a central processing unit (“CPU”), agraphics processing unit (“GPU”), an auxiliary processing unit, a fieldprogrammable gate array (“FPGA”), or similar programmable controller. Insome embodiments, the processor 202 executes instructions stored in thememory 204 to perform the methods and routines described herein. Invarious embodiments, the processor 202 may determine whether to performa two-step random access channel procedure or a four-step random accesschannel procedure. The processor 202 is communicatively coupled to thememory 204, the input device 206, the display 208, the transmitter 210,and the receiver 212.

The memory 204, in one embodiment, is a computer readable storagemedium. In some embodiments, the memory 204 includes volatile computerstorage media. For example, the memory 204 may include a RAM, includingdynamic RAM (“DRAM”), synchronous dynamic RAM (“SDRAM”), and/or staticRAM (“SRAM”). In some embodiments, the memory 204 includes non-volatilecomputer storage media. For example, the memory 204 may include a harddisk drive, a flash memory, or any other suitable non-volatile computerstorage device. In some embodiments, the memory 204 includes bothvolatile and non-volatile computer storage media. In some embodiments,the memory 204 also stores program code and related data, such as anoperating system or other controller algorithms operating on the remoteunit 102.

The input device 206, in one embodiment, may include any known computerinput device including a touch panel, a button, a keyboard, a stylus, amicrophone, or the like. In some embodiments, the input device 206 maybe integrated with the display 208, for example, as a touchscreen orsimilar touch-sensitive display. In some embodiments, the input device206 includes a touchscreen such that text may be input using a virtualkeyboard displayed on the touchscreen and/or by handwriting on thetouchscreen. In some embodiments, the input device 206 includes two ormore different devices, such as a keyboard and a touch panel.

The display 208, in one embodiment, may include any known electronicallycontrollable display or display device. The display 208 may be designedto output visual, audible, and/or haptic signals. In some embodiments,the display 208 includes an electronic display capable of outputtingvisual data to a user. For example, the display 208 may include, but isnot limited to, an LCD display, an LED display, an OLED display, aprojector, or similar display device capable of outputting images, text,or the like to a user. As another, non-limiting, example, the display208 may include a wearable display such as a smart watch, smart glasses,a heads-up display, or the like. Further, the display 208 may be acomponent of a smart phone, a personal digital assistant, a television,a table computer, a notebook (laptop) computer, a personal computer, avehicle dashboard, or the like.

In certain embodiments, the display 208 includes one or more speakersfor producing sound. For example, the display 208 may produce an audiblealert or notification (e.g., a beep or chime). In some embodiments, thedisplay 208 includes one or more haptic devices for producingvibrations, motion, or other haptic feedback. In some embodiments, allor portions of the display 208 may be integrated with the input device206. For example, the input device 206 and display 208 may form atouchscreen or similar touch-sensitive display. In other embodiments,the display 208 may be located near the input device 206.

In some embodiments, in response to determining to perform the two-steprandom access channel procedure: in a first step, the transmitter 210:transmits a preamble in a first time slot; and transmits an uplink datatransmission via a physical uplink shared channel in a second time slotdifferent from the first time slot; and in a second step, the receiver212 receives a response message corresponding to the first step, whereinthe response message comprises a radio network temporary identifier.Although only one transmitter 210 and one receiver 212 are illustrated,the remote unit 102 may have any suitable number of transmitters 210 andreceivers 212. The transmitter 210 and the receiver 212 may be anysuitable type of transmitters and receivers. In one embodiment, thetransmitter 210 and the receiver 212 may be part of a transceiver.

FIG. 3 depicts one embodiment of an apparatus 300 that may be used forperforming a two-step random access channel procedure. The apparatus 300includes one embodiment of the network unit 104. Furthermore, thenetwork unit 104 may include a processor 302, a memory 304, an inputdevice 306, a display 308, a transmitter 310, and a receiver 312. As maybe appreciated, the processor 302, the memory 304, the input device 306,the display 308, the transmitter 310, and the receiver 312 may besubstantially similar to the processor 202, the memory 204, the inputdevice 206, the display 208, the transmitter 210, and the receiver 212of the remote unit 102, respectively.

In various embodiments, the receiver 312 receives a preamble in a firsttime slot and receives an uplink data transmission via a physical uplinkshared channel in a second time slot different from the first time slotin response to a determination by a remote unit to perform a two-steprandom access channel procedure. In some embodiments, the transmitter310 transmits a response message corresponding to the preamble anduplink data transmission, wherein the response message comprises a radionetwork temporary identifier. Although only one transmitter 310 and onereceiver 312 are illustrated, the network unit 104 may have any suitablenumber of transmitters 310 and receivers 312. The transmitter 310 andthe receiver 312 may be any suitable type of transmitters and receivers.In one embodiment, the transmitter 310 and the receiver 312 may be partof a transceiver.

In certain configurations, a CBRA procedure involves the exchange offour messages. In such configurations, when performing a RACH procedureon an unlicensed cell, each of the four messages exchanged during theRACH procedure may undergo a CCA procedure before a transmission may bemade on the unlicensed cell. To reduce time for the RACH procedure, a2-step RACH procedure may be used.

Certain details of a 2-step RACH procedure may include: 1) a formatand/or content of a response message (e.g., in step 2 of the 2-step RACHprocedure); 2) power control issues for a preamble and an uplinktransmission in step 1 of the 2-step RACH procedure; 3) uplink timingfor a PUSCH transmission and a preamble transmission in step 1 of the2-step RACH procedure; 4) switching between a 2-step RACH procedure anda 4-step RACH procedure; and/or 5) resource allocation for an uplinktransmission in step 1 of the 2-step RACH procedure.

FIG. 4 is a communication diagram illustrating one embodiment ofcommunications 400 as part of a RACH procedure (e.g., 4-step RACHprocedure). The communications 400 occur between a UE 402 (e.g., remoteunit 102) and a gNB 404 (e.g., network unit 104, gNB). As may beappreciated, each of the communications 400 described herein may includeone or more messages.

In one embodiment, in a first communication 406 transmitted from the gNB404 to the UE 402, the gNB 404 transmits a SIB to the UE 402. In certainembodiments, in a second communication 408 transmitted from the UE 402to the gNB 404, the UE 402 transmits a PRACH preamble to the gNB 404. Insome embodiments, in a third communication 410 transmitted from the gNB404 to the UE 402, the gNB 404 transmits a RAR to the UE 402.

In various embodiments, in a fourth communication 412 transmitted fromthe UE 402 to the gNB 404, the UE 402 transmits an uplink transmissionon the PUSCH, e.g. connection request message to the gNB 404. In oneembodiment, in a fifth communication 414 transmitted from the gNB 404 tothe UE 402, the gNB 404 transmits a contention resolution message to theUE 402.

As may be appreciated, FIG. 4 shows CBRA. It should be noted that CFRAdoes not include the fourth communication 412 and the fifthcommunication 414. In some embodiments, in CFRA a UE may be allocated aRACH preamble and/or RACH resource (e.g., by means of a PDCCH order)that makes a need for a contention resolution obsolete. An RAR messagemay have the same content for CBRA and CFRA. As may be appreciated, aCFRA may be used for HO, uplink timing alignment, and beam failurerecovery, for example.

As may be appreciated, various embodiments described herein may beapplied to CBRA. Moreover, embodiments described herein may be describedin the context of an unlicensed transmission and/or cell (e.g., NR-U);however, the embodiments herein may also be applicable to licensed cells(e.g., NR or LTE).

FIG. 5 is a communication diagram illustrating another embodiment ofcommunications 500 as part of a RACH procedure (e.g., 2-step RACHprocedure). The communications 500 occur between a UE 502 (e.g., remoteunit 102) and an gNB 504 (e.g., network unit 104, gNB). As may beappreciated, each of the communications 500 described herein may includeone or more messages.

In one embodiment, in a first communication 506 transmitted from the gNB504 to the UE 502, the gNB 504 transmits a SIB to the UE 502. In certainembodiments, in a second communication 508 (e.g., first step in the2-step RACH procedure, msg1 and msg3 of the 4-step RACH procedure)transmitted from the UE 502 to the gNB 504, the UE 502 transmits a PRACHpreamble to the gNB 504 and an uplink transmission (e.g., on PUSCH). Insome embodiments, in a third communication 510 transmitted from the gNB504 to the UE 502, the gNB 504 transmits a RAR and a contentionresolution message to the UE 502 (e.g., second step in the 2-step RACHprocedure, msg2 and msg4 of the 4-step RACH procedure).

In one embodiment, a UE, after having sent in a first step of a 2-stepRACH procedure a preamble-like signal and an initial uplink transmission(e.g., on PUSCH), monitors for one or more response messages (e.g., in asecond step of the 2-step RACH procedure) sent from a gNB. In such anembodiment, the UE may monitor for the one or more response messagesduring a defined time period (e.g., time window). In such an embodiment,the UE monitors during the time window for a PDCCH identified by anRA-RNTI scheduling PDSCH resources on which the one or more responsemessages are transmitted.

In some embodiments, an initial uplink transmission transmitted in afirst step of the 2-step RACH procedure may include a TB containing atleast a UE identifier such as a C-RNTI MAC control element or a UL CCCHSDU. In such embodiments, the TB may contain data of a data radio beareror control information such as a BSR or a PHR.

In various embodiments, a response message (e.g., in step 2 of a 2-stepRACH procedure) sent from a network device (e.g., gNB) in response tothe successful detection of a preamble-like signal (e.g., sent in step 1of the 2-step RACH procedure together with an initial uplinktransmission) contains a random access preamble identifier fieldidentifying a preamble received. In such embodiments, the responsemessage may contain a TA Value that the gNB uses to inform the UE tochange its timing so it may compensate for a round trip delay caused bythe UE distance from the gNB. In certain embodiments, the responsemessage may include an UL grant field within which a gNB may schedule aretransmission of a transport block transmitted in step-1 of a 2-stepRACH procedure or a new initial uplink transmission. In someembodiments, if a TB and/or uplink transmission sent in a first step ofa 2-step RACH procedure along with a preamble-like signal are detectedbut not correctly decoded by a gNB, the gNB may schedule aretransmission of the TB. In such embodiments, because the TB maycontain an identifier identifying a UE, the gNB may decode the TB assoon as possible to resolve a potential contention. In such embodiments,if the TB sent in the first step cannot be correctly decoded by the gNB,the gNB may schedule an additional uplink transmission within theresponse message. In such embodiments, if the TB sent in the first stepcan be correctly decoded by the gNB, the gNB may schedule a furtherinitial uplink transmission within the response message. In certainembodiments, a HARQ process used for the transmission of an uplinktransmission (e.g., on PUSCH) in step 1 of a 2-step RACH procedure maybe predefined, preconfigured, and/or fixed in a standard. It should benoted that an UL grant contained within a response message (e.g., instep 2 of a 2-step RACH procedure) may allocate multiple uplinkresources for an initial transmission or retransmission (e.g., fortransmissions on an unlicensed cell).

In certain embodiments, depending on whether a TB containing anidentifier sent in step 1 of a 2-step RACH procedure is successfullydecoded by a gNB, a response message may contain an ID field echoing theidentifier sent in step 1, thereby resolving a potential contention. Forexample, if an uplink transmission in step 1 containing a C-RNTI MAC CE(e.g., for UEs in an RRC_CONNECTED state having already a C-RNTIallocated) is successfully decoded, the response message may contain aC-RNTI MAC CE set to the same value as the C-RNTI MAC CE sent in step 1.Similarly, as another example, if an uplink transmission sent in step 1containing a UL CCCH SDU (e.g., UE in an RRC_IDLE state) is successfullydecoded, the response message may carry a UE contention resolution IDMAC CE (e.g., first 48 bits of the UL CCCH SDU transmitted in step 1).In some embodiments, if a TB sent in step 1 of a 2-step RACH procedurecannot be successfully decoded, a response message may not contain anidentifier field (e.g., C-RNTI MAC CE or UE contention resolution ID MACCE) because the identity of a UE is not known to a gNB. In suchembodiments, a potential contention may not be resolved (e.g., one ormore further retransmissions of the uplink transmission of step 1 isrequired).

In some embodiments, a response message may contain a temporary C-RNTIfield that may include an identity assigned by a gNB for furthercommunication. In such embodiments, the temporary C-RNTI field may onlybe present in the response message, such as if a TB sent in step 1 of a2-step RACH procedure is not able to be successfully decoded or if theTB sent in step 1 contains a UL CCCH SDU (e.g., if a UE is in anRRC_IDLE state). In certain embodiments, if a UE in an RRC_CONNECTEDstate is performing a 2-step RACH procedure and a TB sent in step 1 ofthe 2-step RACH procedure is successfully decoded by a gNB, a C-RNTIfield may not be used if the UE already has an assigned C-RNTI that isknown to the gNB. In various embodiments, a temporary C-RNTI field isalways present in a response message and a UE may ignore the temporaryC-RNTI field upon reception of the response message if the identifiersent in the response message (e.g., temporary C-RNTI MAC CE) matches anID sent in step 1 of the 2-step RACH procedure.

In one embodiment, a response message of a 2-step RACH procedure istransmitted within a RACH response message transmitted on a PDSCH (e.g.,MAC PDU). In certain embodiments, a UE may monitor upon transmission ofa preamble and an UL transmission during a RACH response window for aresponse message (e.g., PDCCH addressed to RA-RNTI calculated from atimeslot in which the preamble is sent). In some embodiments, a RAPID ina MAC subheader for a random access response indicates whether acorresponding MAC RAR is a legacy RAR or a new response message for a2-step RACH. In various embodiments, certain fields in a MAC RAR (e.g.,MAC payload for a random access response) identify a response for a2-step RACH and a legacy random access response. For example, a reservedbit in a MAC RAR (e.g., see Table 1) may be used to indicate a format ofthe MAC RAR (e.g., response for 2-step RACH or a legacy RAR—4-step RACHRAR).

TABLE 1 MAC RAR R R R Timing Advance Command Timing Advance Command ULGrant UL Grant UL Grant UL Grant Temporary C-RNTI Temporary C-RNTI

In certain embodiments, a first reserved bit set to ‘1’ indicates that aresponse for a 2-step RACH procedure is contained within the MAC RAR. Invarious embodiments, a format for a MAC RAR that includes a response fora 2-step RACH procedure may be different than a legacy MAC RAR format.In one embodiment, a response message for a 2-step RACH may schedule aretransmission of an uplink transmission made in step 1 of the 2-stepRACH procedure. In such an embodiment, an indicator that distinguishesbetween an UL grant for a retransmission and an initial transmission maybe contained in the UL grant field. In certain embodiments, a responsemessage for a 2-step RACH procedure may contain a C-RNTI MAC CE or a UEcontention resolution ID MAC CE (e.g., depending on a decoding status ofa first uplink transmission and a UE RRC state). In various embodiments,a MAC RAR containing a response for 2-step RACH procedure may have avariable size. In one embodiment, extension bits may indicate a presenceof a C-RNTI MAC CE or a UE contention resolution ID MAC CE. In certainembodiments, a response message for a 2-step RACH procedure may containa DL allocation (e.g., either a DL TB or DL grant information pointingto PDSCH resources).

In various embodiments, a RNTI, e.g. RA-RNTI, used for identifying aresponse for a 2-step RACH procedure may be calculated differently(e.g., using a different formula) than the RA-RNTI used for a RAR of alegacy RACH procedure (e.g., 4-step RACH procedure). As used herein, alegacy RACH procedure may refer to a 4-step RACH procedure.

In some embodiments, in response to not receiving a response message instep 2 of a 2-step RACH procedure, a UE may repeat step 1 of the 2-stepRACH procedure and may send a preamble-like signal together with anuplink transmission. In certain embodiments, a UE that does notsuccessfully receive a response message within a defined time window mayassume that a preamble was not detected by a gNB. In variousembodiments, a UE transmits or retransmits a preamble and an uplinktransmission sent previously in step 1 of a 2-step RACH procedure withan increased transmission power than a transmission power used for aprevious transmission of the preamble and the uplink transmission (e.g.,power ramping may be applied to both the preamble and the uplinktransmission).

In one embodiment, a UE switches to a legacy 4-step RACH procedure inthe absence of a response message during a defined time window. In someembodiments, if a UE doesn't successfully receive a response message fora 2-step RACH procedure, the UE switches to the legacy 4-step RACHprocedure and subsequently transmits only a preamble (e.g., no ULtransmission on PUSCH with the preamble). In various embodiments, apreamble transmission may be transmitted with an increased transmissionpower as compared to a previous preamble transmission (e.g., powerramping). In certain embodiments in which different preambles are usedfor a 2-step RACH procedure and a legacy 4-step RACH procedure, a UE mayselect a preamble reserved for the 4-step RACH procedure. In oneembodiment, a UE stores a MAC PDU sent in step 1 of a 2-step RACHprocedure in a Msg3 buffer if switching to a 4-step RACH procedure. Insome embodiments, a new transmission buffer may be used in which a UEstores a MAC PDU sent in step 1 of a 2-step RACH procedure aftergenerating the MAC PDU. As may be appreciated, storing a MAC PDUgenerated for step 1 in a separate buffer may enable laterretransmissions of the generated MAC PDU (e.g., if contention resolutionfails).

In certain embodiments, a UE transmits or retransmits a preambletogether with an uplink (e.g., UL-SCH) transmission in the absence of aresponse message. In such embodiments, the UE may determine whether toapply power ramping (e.g., transmitting with an increased TX powercompared to a previous transmission) for both the preamble and theuplink transmission or for only the preamble. In one embodiment, a UEcalculates a required transmission power for both a preambletransmission P_(preamble) using a power control formula specified forpreamble transmission thereby assuming a predefined power offset and foran uplink transmission P_(UL) using a power control formula specifiedfor the uplink transmission to account for the predefined power offset.It should be noted that the predefined power offset, also referred to asPower_Ramping_Stepsize, may be separately defined for the preambletransmission and the uplink transmission. In certain embodiments, if asum of a required transmission power for a preamble and an uplinktransmission (e.g., including power offsets) does not exceed a UE'stotal maximum transmission power (e.g., P_(CMAX,f,c)(i)), power rampingmay be applied to both the preamble and the uplink transmission. Invarious embodiments, if a sum of P_(Preamble) including a power offsetand P_(UL) without consideration of a power offset doesn't exceedP_(cmax,c), power ramping may only be applied to the preambletransmission. In some embodiments, if P_(Preamble) including a poweroffset and P_(UL) without consideration of a power offset exceedsP_(CMAX,f,c)(i), a UE may switch to a legacy 4-step RACH procedure.

In one embodiment, a UE transmits a preamble-like signal and an uplinkdata transmission conveyed by PUSCH (e.g., elements forming step 1 in a2-step RACH procedure) in different time slots. As may be appreciated,one benefit of transmitting the preamble-like signal and the uplink datatransmission in different time slots may be that a power between thepreamble-like signal and the uplink data transmission does not need tobe shared so that both transmissions may operate at optimum coverage(e.g., optimal power). Further, it should be noted that another benefitof transmitting the preamble-like signal and the uplink datatransmission in different time slots may be that a network node (e.g.,gNB) may first detect the preamble-like transmission, and uponsuccessful detection of the preamble-like transmission proceed toreceive the uplink data transmission. Furthermore, transmitting thepreamble-like signal and the uplink data transmission in different timeslots may eliminate and/or reduce the need for precautionary bufferingof a received time slot.

In some embodiments, different gNB implementations may need a differentamount of time to successfully detect a preamble. Therefore, in oneembodiment, a gNB may configure a time offset that a UE has to observebetween a transmission of a preamble-like signal and a transmission ofuplink data. In such an embodiment, the configuration may be advertised(e.g., in broadcast information in an SIB because all UEs may observethe same offset). In certain embodiments, an offset may depend on anemployed subcarrier spacing (e.g., because a duration of a preamble-likesignal may be a function of the subcarrier spacing) even though arequired detection time may not scale equally. For example, in a firstsubcarrier spacing, an offset may be 1 slot, and in another subcarrierspacing the offset may be 2 slots. As may be appreciated, because it ispossible that a gNB has sufficient capability to buffer a receivedsignal, it may be beneficial if an offset can be 0 slots (e.g., implyingthat a preamble-like signal and an uplink data transmission occur in thesame slot). In various embodiments, an offset of 1 slot may indicatethat a UE is to transmit a preamble-like signal in slot n1, and anuplink data transmission in slot n2=n1+1. In other words, bothtransmissions are adjacent in time. As may be appreciated, this may bebeneficial in an unlicensed carrier configuration in which the UEcontends for channel access (e.g., where any gap may bear the risk oflosing a right to transmit on a channel), or with interference from ahidden node.

In one embodiment, if an offset is larger than 1 slot and if a RACHprocedure occurs on an unlicensed carrier, a UE may perform a clearchannel assessment before transmission of uplink data. As may beappreciated, this may result in not being able to transmit the uplinkdata in a designated slot due to a blocked channel. In certainembodiments, a UE repeats a transmission of a preamble-like signal anduplink data for a number of consecutive slots based on an offset value.In some embodiments, if an offset value is n_o, then a UE may transmitand/or repeat a preamble-like signal during n_o slots followed by uplinkdata transmitted and/or repeated during n_o slots. Accordingly, theremay be no gap from the UE's transmission point of view therebyeliminating (e.g., or reducing) a risk of losing a channel access priorto the uplink data transmission. From the gNB's perspective, if the gNBdetects the preamble-like signal in slot n1, then the gNB may be able toreceive an uplink data signal in slot n1+n_o.

In various embodiments, an offset may be set to a fixed value of 1 slotso that a preamble-like transmission and uplink data transmission occurin adjacent slots. As may be appreciated, this does not require aconfiguration of an offset value and, therefore, uses less overhead thanconfigurations in which the offset is configured via a message and/orsignaling.

In some embodiments, if a transmission of a preamble-like signal anduplink data occur in the same slot, available transmit power of a UE maybe shared. In such embodiments, the preamble-like signal may beprioritized over the uplink data signal so that the preamble-like signalis transmitted with a designated power, and the transmit power of theuplink data signal is reduced to not exceed a total available transmitpower. In such embodiments, a good reception quality of thepreamble-like signal may be made. Having good reception quality for thepreamble-like signa may be more important than good reception quality ofthe uplink data transmission for the RACH procedure. In variousembodiments, if a preamble is detected successfully but an uplink datatransmission cannot be decoded correctly by a gNB, the gNB may still beaware that a RACH procedure has been initiated by the UE, and mayrequest a retransmission of the uplink data.

In certain embodiments, to determine a transmit power of an uplink datatransmission, a UE may use the same power control parameters forcalculating a transmit power P_(PUSCH,b,f,c)(i,j,q_(d),l) of the uplinktransmission in step 1 of the 2-step RACH procedure as the power controlparameters used for a msg3 PUSCH transmission. The power controlparameters may include P_(O_PUSCH,b,f,c), α_(b,f,c,), PL_(b,f,c)(q_(d)).In such embodiments, the PUSCH transmission in step 1 of the 2-step RACHprocedure may be treated as a msg3 PUSCH transmission from a powercontrol perspective. In various embodiments, separate power controlparameters may be defined for a PUSCH transmission in step 1 of a 2-stepRACH procedure (e.g., separate values are defined for P_(O_PUSCH,b,f,c),α_(b,f,c,), PL_(b,f,c)(q_(d)) to satisfy different requirements in termsof reliability (e.g., BLER) or latency). In various embodiments, thefollowing formula may be used:

${P_{{PUSCH},b,f,c}\left( {i,j,q_{d},l} \right)} = {\min\begin{Bmatrix}{{P_{{CMAX},f,c}(i)},} \\\begin{matrix}{{P_{{O\_{PUSCH}},b,f,c}(j)} + {10{\log_{10}\left( {2^{\mu} \cdot {M_{{RB},b,f,c}^{PUSCH}(i)}} \right)}} +} \\{{{\alpha_{b,f,c}(j)} \cdot {{PL}_{b,f,c}\left( q_{d} \right)}} + {\Delta_{{TF},b,f,c}(i)} + {f_{b,f,c}\left( {i,l} \right)}}\end{matrix}\end{Bmatrix}}$

In some embodiments, if a UE is not provided with a higher layerparameter P0-PUSCH-AlphaSet or for a msg3 PUSCH transmission, j=0,P_(O_UE_PUSCH,f,c)(0)=0, andP_(O_NOMINAL_PUSCH,f,c)(0)=P_(O_PRE)+Δ_(PREAMBLE_Msg3), where theparameter preambleReceivedTargetPower (for P_(O_PRE)) andmsg3-DeltaPreamble (for Δ_(PREAMBLE_Msg3)) are provided by higher layersfor carrier f of serving cell c.

For α_(b,f,c)(j), j=0 and α_(b,f,c)(0) is a value of higher layerparameter msg3-Alpha, when provided; otherwise, α_(b,f,c)(0)=1.M_(RB,b,f,c) ^(PUSCH)(i) is the bandwidth of the PUSCH resourceassignment expressed in number of resource blocks for PUSCH transmissionoccasion i on UL BWP b of carrier f of serving cell c and μ may bepredefined. PL_(b,f,c)(q_(d)) is a downlink path-loss estimate in dBcalculated by the UE using reference signal (RS) index q_(d) for a DLBWP that is linked with UL BWP b of carrier f of serving cell c.

If the UE is not provided higher layer parameterPUSCH-PathlossReferenceRS and before the UE is provided dedicated higherlayer parameters, the UE calculates PL_(b,f,c)(q_(d)) using a RSresource from the SS/PBCH block index that the UE obtains higher layerparameter MasterInformationBlock.

If the UE is configured with a number of RS resource indexes up to thevalue of higher layer parameter maxNrofPUSCH-PathlossReferenceRSs and arespective set of RS configurations for the number of RS resourceindexes by higher layer parameter PUSCH-PathlossReferenceRS. The set ofRS resource indexes can include one or both of a set of SS/PBCH blockindexes, each provided by higher layer parameter ssb-Index when a valueof a corresponding higher layer parameter pusch-PathlossReferenceRS-Idmaps to a SS/PBCH block index, and a set of CSI-RS resource indexes,each provided by higher layer parameter csi-RS-Index when a value of acorresponding higher layer parameter pusch-PathlossReferenceRS-Id mapsto a CSI-RS resource index. The UE identifies a RS resource index in theset of RS resource indexes to correspond either to a SS/PBCH block indexor to a CSI-RS resource index as provided by higher layer parameterpusch-PathlossReferenceRS-Id in PUSCH-PathlossReferenceRS.

If the PUSCH is an Msg3 PUSCH, the UE uses the same RS resource index asfor a corresponding PRACH transmission.

PL_(b,f,c)(q_(d)), PL_(f,c)(q_(d))=referenceSignalPower—higher layerfiltered RSRP, where referenceSignalPower is provided by higher layersand RSRP is defined in [7, TS 38.215] for the reference serving cell andthe higher layer filter configuration is defined in [12, TS 38.331] forthe reference serving cell.

For j=0, referenceSignalPower is provided by higher layer parameterss-PBCH-BlockPower. For j>0, referenceSignalPower is configured byeither higher layer parameter ss-PBCH-BlockPower or, when periodicCSI-RS transmission is configured, by higher layer parameterpowerControlOffsetSS providing an offset of the CSI-RS transmissionpower relative to the SS/PBCH block transmission power.

Δ_(TF,b,f,c)(i)=10 log₁₀((2^(BPRE-K),−1)·β_(offset) ^(PUSCH)) forK_(S)=1.25 and Δ_(TF,b,f,c)(i)=0 for K_(S)=0 where K_(S) is provided byhigher layer parameter deltaMCS provided for each UL BWP b of eachcarrier f and serving cell c. If the PUSCH transmission is over morethan one layer [6, TS 38.214], Δ_(TF,b,f,c)(i)=0. BPRE and β_(offset)^(PUSCH), for each UL BWP b of each carrier f and each serving cell c,are computed as below.

${BPRE} = {\underset{r = 0}{\sum\limits^{C - 1}}{K_{r}/N_{RE}}}$for PUSCH with UL-SCH data and BPRE=O_(CSI)/N_(RE) for CSI transmissionin a PUSCH without UL-SCH data, where

C is the number of code blocks, K is the size for code block r, O_(CSI)is the number of CSI part 1 bits including CRC bits, and N_(RE) is thenumber of resource elements determined as

$\begin{matrix}{{N_{RE} = {M\frac{PUSCH}{{RB},b,f,c}{(i) \cdot {\sum\limits_{j = 0}^{{N\frac{PUSCH}{{symb},b,f,c}{(i)}} - 1}{N\frac{RB}{{sc},{data}}\left( {i,j} \right)}}}}},} & \end{matrix}$where

$\begin{matrix}{{N\frac{PUSCH}{{symb},b,f,c}(i)},} & \end{matrix}$is the number of symbols for PUSCH transmission occasion i on UL BWP bof carrier f of serving cell c,

$N\frac{RB}{{sc},{data}}\left( {i,j} \right)$is a number of subcarriers excluding DM-RS subcarriers in PUSCH symbol

$\begin{matrix}{{0 \leq j \leq {N\frac{PUSCH}{{symb},b,f,c}(i)}},} & \end{matrix}$and C, K_(r) are defined in [5, TS 38.212].

β_(offset) ^(PUSCH)=1 when the PUSCH includes UL-SCH data and β_(offset)^(PUSCH)=β_(offset) ^(CSI,1) when the PUSCH includes CSI and does notinclude UL-SCH data.

In certain embodiments, instead of reducing a power of an uplink datatransmission, a UE may defer the uplink data transmission to a laterslot if insufficient power is available for transmission of thepreamble-like signal and the uplink data in the same slot. In someembodiments, to avoid creating transmission gaps on an unlicensedcarrier, it may be advantageous if a UE defers an uplink datatransmission to a next slot after a slot used to transmit apreamble-like signal so that the preamble-like signal and uplink dataare transmitted in adjacent slots. In one embodiment, a gNB performs ablind detection of uplink data at expected resources in the same slotand one or more slots after a detected preamble-like signal. In anotherembodiment, a preamble-like signal indicates whether uplink data istransmitted in the same slot, or deferred to a later slot. For example,a plurality of preamble-like signals forms two or more sets in which thetransmission of a preamble-like signal from a first set indicates thatthe uplink data is transmitted in the same slot as the preamble-likesignal. In such an example, if the preamble-like signal is from a secondset, this indicates that transmission of the uplink data is deferred toa later slot than the preamble-like signal (e.g., to the next slot). Asmay be appreciated, partitioning of the preamble-like signals to setsmay be defined in a communication system, or configured by a network(e.g., by broadcast in system information or by dedicated configurationsignals).

In various embodiments, a timing advance value used for an uplinktransmission in step 1 of a 2-step RACH procedure may be stored andmaintained N_(TA) in a UE for a serving cell on which the uplinktransmission and a preamble transmission take place. It should be notedthat if a TAT expires, a UE maintains N_(TA). In certain configurations,the UE is only allowed to perform a PRACH transmission if TAT isexpired. In some embodiments, the UE performs an uplink transmission onPUSCH, e.g. in step 1 of a 2-step RACH procedure, if the TAT is expired.In some embodiments, a UE uses N_(TA)=0 for an uplink transmission instep 1 of a 2-step RACH procedure. In such embodiments, a preambletransmission and the uplink transmission may use the same timing advancevalue.

As may be appreciated, a UE, before it performs transmission of step 1of a 2-step RACH procedure, may determine which resources may be usedfor transmitting a preamble and an uplink transmission.

In one embodiment, PRACH resources are determined as in a 4-step RACHprocedure (e.g., using RACH-ConfigGeneric parameters broadcasted as partof SIB1 in 5G NR). It should be noted that parameters used to determinePUSCH resources may be broadcast specifically for the purpose oftransmitting step 1 of a 2-step RACH procedure. Accordingly, the PUSCHresources to be used by the UE may have a linking to chosen PRACHresources. The linking may be accomplished using one or more of thefollowing offsets: 1) frequency offset, O_f: offset of lowest PUSCHtransmission occasion in a frequency domain with respective to PRACHresources defined by msg1-FrequencyStart in 5G NR system; and/or 2) timeoffset, T_f: offset of lowest PUSCH transmission occasion in time domainwith respective to PRACH transmission occasion chosen by the UE.

FIG. 6 is a resource diagram 600 illustrating a time offset and afrequency offset. The resource diagram 600 includes a 16×16 grid ofresource elements 602. One resource element 602 is PRB0 “A”, anotherresource element 602 is the PRACH resource “B”. A time offset 604 “T_f”is defined relative to the PRACH resource B to indicate a lowest time“T” in the time domain for a PUSCH transmission. This is illustrated bythe column of resource elements 602 T. A frequency offset 608 “O_f” isdefined relative to the PRACH resource B to indicate a lowest frequency“F” in the frequency domain for a PUSCH transmission. This isillustrated by the row of resource elements 602 F. The intersection ofthe lowest time T and the lowest frequency F is illustrated by resourceelement 602 “C”.

As may be appreciated, a time offset may be a value in a number ofsymbols, a number of slots, or in milliseconds.

In certain embodiments, more than one set of O_f and T_f may bebroadcast such that for one preamble ID or group of preambles IDs, onespecific set of O_f and T_f may be used. For example, if 2 sets of O_fand T_f are broadcast then a first half of the preambles used in thiscell (e.g., 0 . . . 31) may use the first set of O_f and T_f and thesecond half of the preambles used in this cell (e.g., 32 . . . 63) mayuse the second set of O_f and T_f. As may be appreciated, thoughbroadcasting has been indicated above as the signaling mechanism, adedicated RRC signaling or specified values may also be used (e.g., fora non-initial random access procedure).

In various embodiments, a network may configure how many PRBs are usedfor transmitting PUSCH of step 1 of a 2-step RACH procedure using RRCsignaling. In certain embodiments, physical layer parameters like MCSmay be specified or configured using RRC signaling for transmitting thePUSCH of step 1 of a 2-step RACH procedure.

In some embodiments, a UE decides whether to start a 2-step RACHprocedure or a legacy 4-step RACH procedure once an RACH procedure hasbeen triggered depending on certain criteria. In various embodiments, aUE may determine whether to start a 2-step RACH procedure or a 4-stepRACH procedure based on e.g., its power status. In such embodiments, theUE calculates a required transmission power for both a preambletransmission P_(preamble) according to the power control formulaspecified for preamble transmission and for an uplink transmissionP_(UL) according to a power control formula specified for the uplinktransmission. In certain embodiments, if the sum of P_(preamble) andP_(UL) doesn't exceed a UE's total maximum transmission power (e.g.,P_(cmax,c)), a UE starts a 2-step RACH procedure, otherwise the UE usesthe 4-step RACH procedure. In one embodiment, a criterion fordetermining whether to use a 2-step RACH procedure or a 4-step RACHprocedure may be a size of data to be transmitted in an UL transmission(e.g., if the size of the data is above a certain configured threshold,the UE may use the 4-step RACH procedure). In another embodiment, anetwork entity (e.g., such as a gNB) configures whether a UE is enabled,allowed, and/or obliged to perform a 2-step RACH procedure and/or a4-step RACH procedure in a current cell. In such embodiment, theconfiguration may be made per RACH type (e.g., the 2-step RACH procedureis used for handover situations and for scheduling request purposes the4-step RACH procedure is used). In certain embodiments, a PDCCH order ora RRC message ordering a handover may indicate whether to use a legacycontention-free RACH procedure or a 2-step RACH procedure (e.g., ahandover complete message may be included in step 1 of the 2-step RACHprocedure). In various embodiments, a configuration and/or aspecification may indicate that a 2-step RACH procedure is used in anunlicensed spectrum. In certain embodiments, use of a 2-step RACHprocedure or a 4-step RACH procedure may be tied to COT (e.g.,determining to use either the 2-step RACH procedure or the 4-step RACHprocedure based on whether the COT is above and/or below certainthreshold).

In some embodiments, a UE is enabled to use a channel access Type 2(e.g., implying a fixed or shorter sensing interval for a CCA procedure)for transmission of a preamble-like signal and an uplink transmission instep 1 of a 2-step RACH procedure.

FIG. 7 is a flow chart diagram illustrating one embodiment of a method700 for performing a two-step random access channel procedure. In someembodiments, the method 700 is performed by an apparatus, such as theremote unit 102. In certain embodiments, the method 700 may be performedby a processor executing program code, for example, a microcontroller, amicroprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, orthe like.

The method 700 may include determining 702 whether to perform a two-steprandom access channel procedure or a four-step random access channelprocedure. In some embodiments, the method 700 includes, in response todetermining to perform the two-step random access channel procedure: ina first step: transmitting 704 a preamble in a first time slot; andtransmitting an uplink data transmission via a physical uplink sharedchannel in a second time slot different from the first time slot; and,in a second step, receiving a response message corresponding to thefirst step, wherein the response message comprises a radio networktemporary identifier.

In certain embodiments, the method 700 further comprises monitoringduring a response window for the response message. In some embodiments,the radio network temporary identifier for the two-step random accesschannel procedure is calculated using a first formula, and a radionetwork temporary identifier for the four-step random access channelprocedure is calculated using a second formula different from the firstformula. In various embodiments, the uplink data transmission comprisesa medium access control physical data unit.

In one embodiment, the method 700 further comprises storing the mediumaccess control physical data unit in a buffer. In certain embodiments,the medium access control physical data unit is stored in the buffer inresponse to switching from the two-step random access channel procedureto the four-step random access channel procedure. In some embodiments,the method 700 further comprises delaying for an offset time betweentransmission of the preamble and transmission of the uplink datatransmission.

In various embodiments, the offset time corresponds to a subcarrierspacing. In one embodiment, determining whether to perform the two-steprandom access channel procedure or the four-step random access channelprocedure comprises determining whether to perform the two-step randomaccess channel procedure or the four-step random access channelprocedure based on a predetermined factor. In certain embodiments, thepredetermined factor comprises a power status.

In some embodiments, the method 700 further comprises receivinginformation configuring a requirement for performing the two-step randomaccess channel procedure. In various embodiments, the informationindicates that the two-step random access channel procedure is allowed.In one embodiment, the information indicates that the two-step randomaccess channel procedure is required.

FIG. 8 is a flow chart diagram illustrating another embodiment of amethod 800 for performing a two-step random access channel procedure. Insome embodiments, the method 800 is performed by an apparatus, such asthe network unit 104. In certain embodiments, the method 800 may beperformed by a processor executing program code, for example, amicrocontroller, a microprocessor, a CPU, a GPU, an auxiliary processingunit, a FPGA, or the like.

The method 800 may include receiving 802 a preamble in a first time slotand receiving an uplink data transmission via a physical uplink sharedchannel in a second time slot different from the first time slot inresponse to a determination by a remote unit to perform a two-steprandom access channel procedure. In some embodiments, the method 800includes transmitting 804 a response message corresponding to thepreamble, wherein the response message comprises a radio networktemporary identifier.

In certain embodiments, the radio network temporary identifier for thetwo-step random access channel procedure is calculated using a firstformula, and a radio network temporary identifier for a four-step randomaccess channel procedure is calculated using a second formula differentfrom the first formula. In some embodiments, the uplink datatransmission comprises a medium access control physical data unit. Invarious embodiments, an offset time delay is between receiving thepreamble and receiving the uplink data transmission.

In one embodiment, the offset time corresponds to a subcarrier spacing.In certain embodiments, the method 800 further comprises transmittinginformation configuring a requirement for performing the two-step randomaccess channel procedure. In some embodiments, the information indicatesthat the two-step random access channel procedure is allowed. In variousembodiments, the information indicates that the two-step random accesschannel procedure is required.

In one embodiment, a method comprises: determining whether to perform atwo-step random access channel procedure or a four-step random accesschannel procedure; and, in response to determining to perform thetwo-step random access channel procedure: in a first step: transmittinga preamble in a first time slot; and transmitting an uplink datatransmission via a physical uplink shared channel in a second time slotdifferent from the first time slot; and, in a second step, receiving aresponse message corresponding to the first step, wherein the responsemessage comprises a radio network temporary identifier.

In certain embodiments, the method further comprises monitoring during aresponse window for the response message.

In some embodiments, the radio network temporary identifier for thetwo-step random access channel procedure is calculated using a firstformula, and a radio network temporary identifier for the four-steprandom access channel procedure is calculated using a second formuladifferent from the first formula.

In various embodiments, the uplink data transmission comprises a mediumaccess control physical data unit.

In one embodiment, the method further comprises storing the mediumaccess control physical data unit in a buffer.

In certain embodiments, the medium access control physical data unit isstored in the buffer in response to switching from the two-step randomaccess channel procedure to the four-step random access channelprocedure.

In some embodiments, the method further comprises delaying for an offsettime between transmission of the preamble and transmission of the uplinkdata transmission.

In various embodiments, the offset time corresponds to a subcarrierspacing.

In one embodiment, determining whether to perform the two-step randomaccess channel procedure or the four-step random access channelprocedure comprises determining whether to perform the two-step randomaccess channel procedure or the four-step random access channelprocedure based on a predetermined factor.

In certain embodiments, the predetermined factor comprises a powerstatus.

In some embodiments, the method further comprises receiving informationconfiguring a requirement for performing the two-step random accesschannel procedure.

In various embodiments, the information indicates that the two-steprandom access channel procedure is allowed.

In one embodiment, the information indicates that the two-step randomaccess channel procedure is required.

In one embodiment, an apparatus comprises: a processor that determineswhether to perform a two-step random access channel procedure or afour-step random access channel procedure; a transmitter; and areceiver, wherein in response to determining to perform the two-steprandom access channel procedure: in a first step, the transmitter:transmits a preamble in a first time slot; and transmits an uplink datatransmission via a physical uplink shared channel in a second time slotdifferent from the first time slot; and in a second step, the receiverreceives a response message corresponding to the first step, wherein theresponse message comprises a radio network temporary identifier.

In certain embodiments, the processor monitors during a response windowfor the response message.

In some embodiments, the radio network temporary identifier for thetwo-step random access channel procedure is calculated using a firstformula, and a radio network temporary identifier for the four-steprandom access channel procedure is calculated using a second formuladifferent from the first formula.

In various embodiments, the uplink data transmission comprises a mediumaccess control physical data unit.

In one embodiment, the apparatus further comprising a buffer that storesthe medium access control physical data unit.

In certain embodiments, the medium access control physical data unit isstored in the buffer in response to switching from the two-step randomaccess channel procedure to the four-step random access channelprocedure.

In some embodiments, the processor delays for an offset time betweentransmission of the preamble and transmission of the uplink datatransmission.

In various embodiments, the offset time corresponds to a subcarrierspacing.

In one embodiment, the processor determines whether to perform thetwo-step random access channel procedure or the four-step random accesschannel procedure by determining whether to perform the two-step randomaccess channel procedure or the four-step random access channelprocedure based on a predetermined factor.

In certain embodiments, the predetermined factor comprises a powerstatus.

In some embodiments, the receiver receives information configuring arequirement for performing the two-step random access channel procedure.

In various embodiments, the information indicates that the two-steprandom access channel procedure is allowed.

In one embodiment, the information indicates that the two-step randomaccess channel procedure is required.

In one embodiment, a method comprises: receiving a preamble in a firsttime slot and receiving an uplink data transmission via a physicaluplink shared channel in a second time slot different from the firsttime slot in response to a determination by a remote unit to perform atwo-step random access channel procedure; and transmitting a responsemessage corresponding to the preamble, wherein the response messagecomprises a radio network temporary identifier.

In certain embodiments, the radio network temporary identifier for thetwo-step random access channel procedure is calculated using a firstformula, and a radio network temporary identifier for a four-step randomaccess channel procedure is calculated using a second formula differentfrom the first formula.

In some embodiments, the uplink data transmission comprises a mediumaccess control physical data unit.

In various embodiments, an offset time delay is between receiving thepreamble and receiving the uplink data transmission.

In one embodiment, the offset time corresponds to a subcarrier spacing.

In certain embodiments, the method further comprises transmittinginformation configuring a requirement for performing the two-step randomaccess channel procedure.

In some embodiments, the information indicates that the two-step randomaccess channel procedure is allowed.

In various embodiments, the information indicates that the two-steprandom access channel procedure is required.

In one embodiment, an apparatus comprises: a receiver that receives apreamble in a first time slot and receiving an uplink data transmissionvia a physical uplink shared channel in a second time slot differentfrom the first time slot in response to a determination by a remote unitto perform a two-step random access channel procedure; and a transmitterthat transmits a response message corresponding to the preamble, whereinthe response message comprises a radio network temporary identifier.

In certain embodiments, the radio network temporary identifier for thetwo-step random access channel procedure is calculated using a firstformula, and a radio network temporary identifier for a four-step randomaccess channel procedure is calculated using a second formula differentfrom the first formula.

In some embodiments, the uplink data transmission comprises a mediumaccess control physical data unit.

In various embodiments, an offset time delay is between receiving thepreamble and receiving the uplink data transmission.

In one embodiment, the offset time corresponds to a subcarrier spacing.

In certain embodiments, the transmitter transmits informationconfiguring a requirement for performing the two-step random accesschannel procedure.

In some embodiments, the information indicates that the two-step randomaccess channel procedure is allowed.

In various embodiments, the information indicates that the two-steprandom access channel procedure is required.

Embodiments may be practiced in other specific forms. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

The invention claimed is:
 1. A method comprising: receivingconfiguration information from a network device indicating whethertwo-step random access resources are configured and whether four-steprandom access resources are configured; determining whether to perform atwo-step random access channel procedure or a four-step random accesschannel procedure based on a reference signal received power of adownlink pathloss reference and the configuration information, whereinthe two-step random access channel procedure is determined to beperformed in response to the reference signal received power beinggreater than a configured threshold and the configuration informationindicating that two-step random access resources and four-step randomaccess resources are configured; and in response to determining toperform the two-step random access channel procedure: in a first step:transmitting a preamble in a first time instance; and transmitting anuplink data transmission via a physical uplink shared channel in asecond time instance different from the first time instance; and in asecond step, monitoring for a response message corresponding to thefirst step during a time window, wherein the response message isindicated by a radio network temporary identifier.
 2. The method ofclaim 1, wherein the radio network temporary identifier for the two-steprandom access channel procedure is calculated using a first formula, anda radio network temporary identifier for the four-step random accesschannel procedure is calculated using a second formula different fromthe first formula.
 3. The method of claim 1, wherein a physical uplinkshared channel resource used for the uplink data transmission in thefirst step is linked to the preamble transmitted in the first step. 4.The method of claim 1, wherein the uplink data transmission comprises amedium access control protocol data unit.
 5. The method of claim 4,further comprising storing the medium access control protocol data unitin a first buffer.
 6. The method of claim 5, wherein the medium accesscontrol protocol data unit is stored in a second buffer in response toswitching from the two-step random access channel procedure to thefour-step random access channel procedure.
 7. The method of claim 6,wherein the second buffer is a msg3 buffer.
 8. The method of claim 1,wherein the transmission of the preamble and the transmission of theuplink data transmission occur in different slots.
 9. The method ofclaim 1, wherein an offset between the transmission of the preamble andtransmission of the uplink data transmission is configured by a networkentity.
 10. An apparatus comprising a user equipment, the apparatusfurther comprising: a receiver that receives configuration informationfrom a network device indicating whether two-step random accessresources are configured and whether four-step random access resourcesare configured; a processor that determines whether to perform atwo-step random access channel procedure or a four-step random accesschannel procedure based on a reference signal received power of adownlink pathloss reference and the configuration information, whereinthe two-step random access channel procedure is determined to beperformed in response to the reference signal received power beinggreater than a configured threshold and the configuration informationindicating that two-step random access resources and four-step randomaccess resources are configured; and a transmitter; wherein in responseto determining to perform the two-step random access channel procedure:in a first step, the transmitter: transmits a preamble in a first timeinstance; and transmits an uplink data transmission via a physicaluplink shared channel in a second time instance different from the firsttime instance; and in a second step, the processor monitors for aresponse message corresponding to the first step during a time window,wherein the response message is indicated by a radio network temporaryidentifier.
 11. The apparatus of claim 10, wherein the radio networktemporary identifier for the two-step random access channel procedure iscalculated using a first formula, and a radio network temporaryidentifier for the four-step random access channel procedure iscalculated using a second formula different from the first formula. 12.The apparatus of claim 10, wherein a physical uplink shared channelresource used for the uplink data transmission in the first step islinked to the preamble transmitted in the first step.
 13. The apparatusof claim 10, wherein the receiver receives information configuring arequirement for performing the two-step random access channel procedure.14. The apparatus of claim 13, wherein the information indicates thatthe two-step random access channel procedure is allowed.
 15. Anapparatus comprising: a transmitter that transmits configurationinformation from a network device indicating whether two-step randomaccess resources are configured and whether four-step random accessresources are configured; and a receiver that receives a preamble in afirst time instance and receives an uplink data transmission via aphysical uplink shared channel in a second time instance different fromthe first time instance in response to a determination by a remote unitto perform a two-step random access channel procedure, wherein thedetermination by the remote unit to perform the two-step random accesschannel procedure is based on a reference signal received power of adownlink pathloss reference and the configuration information, and thetwo-step random access channel procedure is determined to be performedin response to the reference signal received power being greater than aconfigured threshold and the configuration information indicating thatthe two-step random access channel procedure and the four-step randomaccess channel procedure are configured; wherein the transmittertransmits a response message corresponding to the preamble, and theresponse message comprises a radio network temporary identifier.
 16. Theapparatus of claim 15, wherein the transmitter transmits informationconfiguring a requirement for performing the two-step random accesschannel procedure.
 17. The apparatus of claim 16, wherein theinformation indicates that the two-step random access channel procedureis allowed.
 18. The apparatus of claim 16, wherein the informationindicates that the two-step random access channel procedure is required.19. The apparatus of claim 15, wherein the radio network temporaryidentifier for the two-step random access channel procedure iscalculated using a first formula, and a radio network temporaryidentifier for the four-step random access channel procedure iscalculated using a second formula different from the first formula. 20.The apparatus of claim 15, wherein a physical uplink shared channelresource used for the uplink data transmission is linked to thepreamble.